Line data Source code
1 : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 : Copyright (c) 2012-2023 The plumed team
3 : (see the PEOPLE file at the root of the distribution for a list of names)
4 :
5 : See http://www.plumed.org for more information.
6 :
7 : This file is part of plumed, version 2.
8 :
9 : plumed is free software: you can redistribute it and/or modify
10 : it under the terms of the GNU Lesser General Public License as published by
11 : the Free Software Foundation, either version 3 of the License, or
12 : (at your option) any later version.
13 :
14 : plumed is distributed in the hope that it will be useful,
15 : but WITHOUT ANY WARRANTY; without even the implied warranty of
16 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 : GNU Lesser General Public License for more details.
18 :
19 : You should have received a copy of the GNU Lesser General Public License
20 : along with plumed. If not, see <http://www.gnu.org/licenses/>.
21 : +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
22 : #include "SecondaryStructureRMSD.h"
23 : #include "core/ActionShortcut.h"
24 : #include "core/ActionRegister.h"
25 :
26 : namespace PLMD {
27 : namespace secondarystructure {
28 :
29 : //+PLUMEDOC COLVAR ALPHARMSD
30 : /*
31 : Probe the alpha helical content of a protein structure.
32 :
33 : Any chain of six contiguous residues in a protein chain can form an alpha helix. This
34 : colvar thus generates the set of all possible six residue sections and calculates
35 : the RMSD distance between the configuration in which the residues find themselves
36 : and an idealized alpha helical structure. These distances can be calculated by either
37 : aligning the instantaneous structure with the reference structure and measuring each
38 : atomic displacement or by calculating differences between the set of inter-atomic
39 : distances in the reference and instantaneous structures.
40 :
41 : This colvar is based on the following reference \cite pietrucci09jctc. The authors of
42 : this paper use the set of distances from the alpha helix configurations to measure
43 : the number of segments that have an alpha helical configuration. This is done by calculating
44 : the following sum of functions of the rmsd distances:
45 :
46 : \f[
47 : s = \sum_i \frac{ 1 - \left(\frac{r_i-d_0}{r_0}\right)^n } { 1 - \left(\frac{r_i-d_0}{r_0}\right)^m }
48 : \f]
49 :
50 : where the sum runs over all possible segments of alpha helix. By default the
51 : NN, MM and D_0 parameters are set equal to those used in \cite pietrucci09jctc. The R_0
52 : parameter must be set by the user - the value used in \cite pietrucci09jctc was 0.08 nm.
53 :
54 : If you change the function in the above sum you can calculate quantities such as the average
55 : distance from a purely the alpha helical configuration or the distance between the set of
56 : residues that is closest to an alpha helix and the reference configuration. To do these sorts of
57 : calculations you can use the AVERAGE and MIN keywords. In addition you can use the LESS_THAN
58 : keyword if you would like to change the form of the switching function. If you use any of these
59 : options you no longer need to specify NN, R_0, MM and D_0.
60 :
61 : Please be aware that for codes like gromacs you must ensure that plumed
62 : reconstructs the chains involved in your CV when you calculate this CV using
63 : anything other than TYPE=DRMSD. For more details as to how to do this see \ref WHOLEMOLECULES.
64 :
65 : \par Examples
66 :
67 : The following input calculates the number of six residue segments of
68 : protein that are in an alpha helical configuration.
69 :
70 : \plumedfile
71 : #SETTINGS MOLFILE=regtest/basic/rt32/helix.pdb
72 : MOLINFO STRUCTURE=helix.pdb
73 : alpha: ALPHARMSD RESIDUES=all
74 : \endplumedfile
75 :
76 : Here the same is done use RMSD instead of DRMSD
77 :
78 : \plumedfile
79 : #SETTINGS MOLFILE=regtest/basic/rt32/helix.pdb
80 : MOLINFO STRUCTURE=helix.pdb
81 : WHOLEMOLECULES ENTITY0=1-100
82 : alpha: ALPHARMSD RESIDUES=all TYPE=OPTIMAL R_0=0.1
83 : \endplumedfile
84 :
85 : */
86 : //+ENDPLUMEDOC
87 :
88 : class AlphaRMSD : public ActionShortcut {
89 : public:
90 : static void registerKeywords( Keywords& keys );
91 : explicit AlphaRMSD(const ActionOptions&);
92 : };
93 :
94 : PLUMED_REGISTER_ACTION(AlphaRMSD,"ALPHARMSD")
95 :
96 9 : void AlphaRMSD::registerKeywords( Keywords& keys ) {
97 9 : SecondaryStructureRMSD::registerKeywords( keys );
98 18 : keys.setValueDescription("scalar/vector","if LESS_THAN is present the RMSD distance between each residue and the ideal alpha helix. If LESS_THAN is not present the number of residue segments where the structure is similar to an alpha helix");
99 36 : keys.remove("ATOMS"); keys.remove("SEGMENT"); keys.remove("BONDLENGTH"); keys.remove("CUTOFF_ATOMS");
100 27 : keys.remove("NO_ACTION_LOG"); keys.remove("STRANDS_CUTOFF"); keys.remove("STRUCTURE");
101 9 : }
102 :
103 3 : AlphaRMSD::AlphaRMSD(const ActionOptions&ao):
104 : Action(ao),
105 3 : ActionShortcut(ao)
106 : {
107 : // Read in the input and create a string that describes how to compute the less than
108 3 : std::string ltmap; bool uselessthan=SecondaryStructureRMSD::readShortcutWords( ltmap, this );
109 : // read in the backbone atoms
110 3 : std::vector<unsigned> chains; std::string atoms; SecondaryStructureRMSD::readBackboneAtoms( this, plumed, "protein", chains, atoms );
111 :
112 : // This constructs all conceivable sections of alpha helix in the backbone of the chains
113 3 : unsigned nprevious=0, segno=1; std::string seglist;
114 6 : for(unsigned i=0; i<chains.size(); ++i) {
115 3 : if( chains[i]<30 ) error("segment of backbone defined is not long enough to form an alpha helix. Each backbone fragment must contain a minimum of 6 residues");
116 3 : unsigned nres=chains[i]/5;
117 3 : if( chains[i]%5!=0 ) error("backbone segment received does not contain a multiple of five residues");
118 18 : for(unsigned ires=0; ires<nres-5; ires++) {
119 15 : unsigned accum=nprevious + 5*ires; std::string strval, num; Tools::convert( segno, num );
120 30 : Tools::convert( accum, strval ); seglist += " SEGMENT" + num + "=" + strval;
121 450 : for(unsigned k=1; k<30; ++k) { Tools::convert( accum+k, strval ); seglist += "," + strval; }
122 15 : segno++;
123 : }
124 3 : nprevious+=chains[i];
125 : }
126 :
127 : // Build the reference structure ( in angstroms )
128 3 : std::vector<Vector> reference(30);
129 3 : reference[0] = Vector( 0.733, 0.519, 5.298 ); // N i
130 3 : reference[1] = Vector( 1.763, 0.810, 4.301 ); // CA
131 3 : reference[2] = Vector( 3.166, 0.543, 4.881 ); // CB
132 3 : reference[3] = Vector( 1.527, -0.045, 3.053 ); // C
133 3 : reference[4] = Vector( 1.646, 0.436, 1.928 ); // O
134 3 : reference[5] = Vector( 1.180, -1.312, 3.254 ); // N i+1
135 3 : reference[6] = Vector( 0.924, -2.203, 2.126 ); // CA
136 3 : reference[7] = Vector( 0.650, -3.626, 2.626 ); // CB
137 3 : reference[8] = Vector(-0.239, -1.711, 1.261 ); // C
138 3 : reference[9] = Vector(-0.190, -1.815, 0.032 ); // O
139 3 : reference[10] = Vector(-1.280, -1.172, 1.891 ); // N i+2
140 3 : reference[11] = Vector(-2.416, -0.661, 1.127 ); // CA
141 3 : reference[12] = Vector(-3.548, -0.217, 2.056 ); // CB
142 3 : reference[13] = Vector(-1.964, 0.529, 0.276 ); // C
143 3 : reference[14] = Vector(-2.364, 0.659, -0.880 ); // O
144 3 : reference[15] = Vector(-1.130, 1.391, 0.856 ); // N i+3
145 3 : reference[16] = Vector(-0.620, 2.565, 0.148 ); // CA
146 3 : reference[17] = Vector( 0.228, 3.439, 1.077 ); // CB
147 3 : reference[18] = Vector( 0.231, 2.129, -1.032 ); // C
148 3 : reference[19] = Vector( 0.179, 2.733, -2.099 ); // O
149 3 : reference[20] = Vector( 1.028, 1.084, -0.833 ); // N i+4
150 3 : reference[21] = Vector( 1.872, 0.593, -1.919 ); // CA
151 3 : reference[22] = Vector( 2.850, -0.462, -1.397 ); // CB
152 3 : reference[23] = Vector( 1.020, 0.020, -3.049 ); // C
153 3 : reference[24] = Vector( 1.317, 0.227, -4.224 ); // O
154 3 : reference[25] = Vector(-0.051, -0.684, -2.696 ); // N i+5
155 3 : reference[26] = Vector(-0.927, -1.261, -3.713 ); // CA
156 3 : reference[27] = Vector(-1.933, -2.219, -3.074 ); // CB
157 3 : reference[28] = Vector(-1.663, -0.171, -4.475 ); // C
158 3 : reference[29] = Vector(-1.916, -0.296, -5.673 ); // O
159 : std::string ref0, ref1, ref2;
160 3 : Tools::convert( reference[0][0], ref0 );
161 3 : Tools::convert( reference[0][1], ref1 );
162 3 : Tools::convert( reference[0][2], ref2 );
163 6 : std::string structure=" STRUCTURE1=" + ref0 + "," + ref1 + "," + ref2;
164 90 : for(unsigned i=1; i<30; ++i) {
165 348 : for(unsigned k=0; k<3; ++k) { Tools::convert( reference[i][k], ref0 ); structure += "," + ref0; }
166 : }
167 :
168 6 : std::string type; parse("TYPE",type); std::string lab = getShortcutLabel() + "_rmsd"; if( uselessthan ) lab = getShortcutLabel();
169 6 : std::string nopbcstr=""; bool nopbc; parseFlag("NOPBC",nopbc); if( nopbc ) nopbcstr = " NOPBC";
170 6 : readInputLine( lab + ": SECONDARY_STRUCTURE_RMSD BONDLENGTH=0.17" + seglist + structure + " " + atoms + " TYPE=" + type + nopbcstr );
171 : // Create the less than object
172 3 : if( ltmap.length()>0 ) SecondaryStructureRMSD::expandShortcut( uselessthan, getShortcutLabel(), lab, ltmap, this );
173 3 : }
174 :
175 : }
176 : }
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